The urea cycle rids the body of excess nitrogen by converting it to a nontoxic form that can be excreted in the urine. It utilizes one nitrogen atom from carbamoyl phosphate and one nitrogen atom from aspartate. There are four enzymes in the cycle. Which enzyme releases urea as a product? ornithine transcarbamoylase argininosuccinate synthetase arginase argininosuccinase Which enzyme requires ATP?

1. Arginase

2. Argininosuccinate synthetase

Explanation:

1. It is the enzyme Arginase which is responsible for production of urea and regeneration of ornithine from arginine.

Thus, option C is correct

2. In the ornithine cycle in the liver cells extra proteins with in the body are degraded by deamination process in which NH2group is removed and converted into NH4 + ions.

This NH4 + combines with carbon dioxide by using 2 ATP molecules in the presence of enzyme carbomyl phosphate synthase. Carbomyl phosphate is then converted into citrulline in presence of enzyme ornithine transcarbamoylase. In the next stage, argininosuccinate is formed by addition of amino group of aspartate and the carbonyl group of citrulline in presence of argininosuccinate synthetase which derives its energy from ATP molecule.

Thus, enzyme argininosuccinate synthetase requires ATP